1. Field
Embodiments of the present invention relate to a control valve filter and a control valve insertion structure, which are attached to an external periphery of a control valve to prevent a foreign object from mixing into the control valve.
2. Description of Related Art
A hydraulic control system of an engine and the like uses many control valves for controlling the hydraulic pressure of a control fluid such as oil or switching the hydraulic path. With such a control valve, when a foreign object mixed in the oil enters into the main body of the control valve or the foreign object is discharged therefrom, a sliding member such as a valve plug provided in the inside of the control valve may fail to perform stable operation, or there may be a malfunction in the operation of an actuator operated hydraulically, and therefore, a port unit which is formed to be open in the external periphery of the main body of the control valve is covered with a control valve filter, which prevents a foreign object mixed in oil from flowing to the actuator.
What is described in Patent Literature 1 to Patent Literature 3 are known as such control valve filters.
A control valve filter as described in Patent Literature 1 includes a substantially ring-shaped frame and a filter member provided on this frame, and a divided portion is formed at a portion of the frame, and an engagement unit is formed at this divided portion. This engagement unit is formed with a recessed portion and a projection portion, and the recessed portion and the projection portion are brought closer to each other in a peripheral direction, and the recessed portion and the projection portion are engaged with each other by a fitting which is called snap-fit, i.e., the projection portion is elastically pushed into the recessed portion to be fit thereinto.
Patent Literature 1 also indicates that the divided portion of the substantially ring-shaped frame is fit into a stud, and is coupled by spot welding.
A control valve filter as described in Patent Literature 2 includes a substantially ring-shaped frame and a filter member provided on this frame, and a divided portion is formed at a portion of the frame. One end of the divided portion is provided with a hook unit whose end is bent in such a manner that the hook unit protrudes to the other end of the divided portion, and the other end of the divided portion is provided with a retaining unit capable of engaging with the hook unit, and further, a claw unit is provided on the frame. Then, the hook unit is pushed into the retaining unit while the claw unit is elastically pushed, so that the hook unit is engaged with the retaining unit.
A control valve filter as described in Patent Literature 3 includes a substantially ring-shaped frame and a filter member provided on this frame, and a divided portion is formed at a portion of the frame. First and second abutment units engaging with each other are formed at the divided portion. The first abutment unit is formed with first and second elastic engagement units extending in a substantially tangential line direction so that the first and second elastic engagement units are displaced in a plate thickness direction with a width substantially half of the width in the width direction of the frame body, and the second abutment unit is formed with third and fourth elastic engagement units engaging with the first and second elastic engagement units, respectively, in such a manner that the third and fourth elastic engagement units extend in a substantially tangential line direction so that the third and fourth elastic engagement units are displaced in a plate thickness direction with a width substantially half of the width in the width direction of the frame body, and the third and fourth elastic engagement units are formed to face the first and second elastic engagement units, respectively, so that the third and fourth elastic engagement units are displaced oppositely in the plate thickness direction. Then, the first and second elastic engagement units are engaged with the third and fourth elastic engagement units, respectively, so that the divided portion is engaged.